Water intrusion in forward most ceiling light - where is it coming from?

[ShrimpBurrito]

I just started getting some water intruding into the lens cover of the forward most ceiling light on the front shell -- just in front of those cabinets in the front of the front shell.

Presumably, there are only 3 places the water can be coming from. I'm thinking more than likely it's coming from the center roof seam, but on a quick check at least, the strip covering it on the roof seems solid. It still could be that, though I'm now also wondering if it could be either side where the roof meets the walls, or the TV antenna. Has anyone ever had a leak here before?

Alternatively, has anyone ever used any sort of "leak finder" dye solution?

Dave